Nairobi - Activists accused South Sudan's government on Monday of funnelling cash from the state oil company to militias responsible for atrocities and attacks on civilians.
South Sudan dismissed the report by The Sentry, a group co-founded by actor George Clooney. "The oil money did not even ... buy a knife. It is being used for paying the salaries of the civil servants," said presidential spokesman Ateny Wek Ateny.
The Sentry said it had found documents, including payment logs from state oil operator Nilepet, suggesting that cash from the company had been used to fund fighters caught up in the country's civil war. Nilepet was not immediately available for comment.
"The documents appear to describe how top officials used Nilepet funds to support a group of (ethnic) Padang Dinka militias active in northeastern Upper Nile state and implicated in widespread attacks against civilians and other atrocities," the Washington D.C.-based group said in a statement.
South Sudan has been racked by an ethnically charged civil war since late 2013, pitting forces loyal to President Salva Kiir, a member of the Dinka group, against rebels linked to former vice president Riek Machar, a Nuer.
The Sentry said it had also received a log kept by South Sudan's Ministry of Petroleum and Mining detailing $80 million worth of security-related payments made by Nilepet.
It did not publish any of the documents and Reuters was not able to verify the accusations independently.
The ministry of petroleum had funded food, fuel and satellite phone airtime and sent money to militias accused of attacking civilians, The Sentry said.
"They have used the country's oil to buy weapons, fund deadly militias, and hire companies owned by political insiders to support military operations that have resulted in horrific atrocities and war crimes," J.R. Mailey, who leads special investigations at The Sentry, said in a statement.
The government dismissed the accusations as a fabrication designed to damage its image.
"South Sudan is not looking for guns now, South Sudan is at peace. I don't know why The Sentry is putting wrong stories against South Sudan," Ateny told Reuters.
The United States and other powers have been stepping up pressure on South Sudan to stop the war, which erupted less than two years after the country declared independence from Sudan.
Last month the US imposed an arms embargo, following sanctions on some South Sudan leaders late last year.
UN investigators last month said they had identified more than 40 South Sudanese military officers who may be responsible for war crimes and crimes against humanity. Their report detailed mutilations, sexual crimes and killings of civilians.
The war has forced more than 4 million South Sudanese to flee their homes, creating Africa's largest refugee crisis since the 1994 Rwandan genocide.